Optical apparatus provided with demultiplexing function

Abstract

The present invention has an object to provide an optical apparatus of VIPA-type for achieving the reduction of the inter-channel loss deviation to realize a high accurate demultiplexing function. To this end, the optical apparatus according to the present invention comprises: a collimator lens converting an input light into a parallel light; a phase mask changing a phase of the parallel light from the collimator lens to change the intensity distribution into a shape different from the Gaussian distribution; a line focal lens condensing the light output from the phase mask onto a one-dimensional direction; and a VIPA plate multi-reflecting the light condensed by the line focal lens to emit the multi-reflected light.

1. An optical apparatus provided with a function of demultiplexing a wavelength division multiplexed light, comprising: a first lens converting an input light into a parallel light; a second lens condensing the parallel light converted by said first lens onto a one-dimensional direction; and an optical device having opposed parallel reflective planes in which the light condensed by said second lens is incident between said respective reflective planes in parallel to the planes, a part of said incident light is transmitted through one of the reflective planes to be emitted while said incident light being multi-reflected by the respective reflective planes, and the emitted lights interfere with each other to form a plurality of optical beams traveling directions of which are different from each other, according to wavelengths,
 wherein said apparatus further comprises an element changing an optical phase which is disposed between said first and second lenses, and the parallel light converted by said first lens is given to said second lens via said element. 
 
     
     
       2. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said element changing the optical phase changes a phase of the parallel light converted by said first lens to adjust the intensity distribution of the light to be given to said second lens, so that a condensation image of said second lens approaches an inversed Fourier transformed image of a target diffraction image of the light emitted from said optical device. 
 
     
     
       3. An optical apparatus provided with a demultiplexing function according to  claim 2 ,
 wherein said element changing the optical phase changes the phase of the parallel light converted by said first lens to adjust the intensity distribution of the light to be given to said second lens, so that the intensity distribution of the condensation image of said second lens follows a function of sin(y)/y type, provided that a direction vertical to an optical axis direction of the light incident on said optical device from said second lens is y-axis. 
 
     
     
       4. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said element changing the optical phase is formed of a substrate having the substantially uniform refractive index, and the thickness of said substrate in an optical propagation direction is made uneven in spatial. 
 
     
     
       5. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said element changing the optical phase is formed of a substrate having the substantially uniform thickness in an optical propagation direction, and the refractive index of said substrate is made uneven in spatial. 
 
     
     
       6. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said element changing the optical phase is subjected to the non-reflective coating on optical incidence and emission planes thereof. 
 
     
     
       7. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said element changing the optical phase is provided with a temperature control function for controlling a phase change given to a transmitted light to be constant, regardless of a temperature variation. 
 
     
     
       8. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said second lens is a cylindrical lens. 
 
     
     
       9. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said second lens is a refractive index profile lens. 
 
     
     
       10. An optical apparatus provided with a demultiplexing function according to  claim 1 ,
 wherein said optical device is configured such that the reflectance of one of the reflective planes thereof is lower than 100% and the reflectance of the other reflective plane is approximately 100%, and includes a radiation window at which the optical reflection can be substantially neglected, on an incident portion of the light condensed by said second lens. 
 
     
     
       11. An optical apparatus provided with a demultiplexing function according to  claim 1 , further comprising a third lens condensing the optical beams emitted from said optical device for each wavelength,
 wherein the light emitted from an input side optical fiber is given to said first lens, and the light condensed by said third lens is introduced to an output side optical fiber corresponding to each wavelength.